Under-reamers



C A. DEAN UNDER-REAMERS Jan. 13, 1959 2 Sheets-Sheet 1 Filed Dec. 30, 1955 INVENTO-R CHARLES A. DEAN ATTORNEY Jan. 13, 1959 I c. A. DEAN UNDER-REAMERS 2 Sheets-Sheet 2 Filed De:-v 50, 1955 FIG?) I INVENTOR CHARLES. A. DEAN .may readily settle and clog a drill.

United States Patent 2,868,510 UNDER-REAMERS Charles A. Dean, Los Angeles, Calif. Application December 30, 1955, Serial No. 556,586 6 Claims. (Cl. 255-76) This invention relates to earth-boring drills, particularly to improvements in under-reamer drills. The underreamer drill operates at some intermediate depth of a bore. This reamer forms an intermediate part of a drill string, being threaded at each end into the string above the usual bottom cutters and being a continuing, though removable, part of the drill string. The present invention provides an under-reamer that is usable to ream repeatedly, at whatever intermediate depths, without withdrawing the drill from the bore and without interfering with normal drilling or deepening at the bottom of the hole. This reamer cuts enlargements in an existing bore as well as straightens a bore.

This under-rearner may at times be kept in inactive posi tion but is ready at any time, even repeatedly, to ream the bore walls. It may be required to enlarge the bore at some intermediate point where a casing may have parted, or even where no casing has been placed. This invention deals with means to obtain considerable flexibility in uses of an under-reamer and deals also with locking means to keep the reamer inactive at will whether in a casing or not. Also, this reamer may be unlocked or relocked at will repeatedly at any place in the drill hole.

An under-reamer should operate under various conditions. As one example, the bore being drilled may curve considerably from a straight line. Sometimes this is brought about intentionally in order to explore or to tap earth strata even far to the side of the drill rig. At other times sidewise wandering of the drill is unintentional. Wherever the bore is curved, the upper side is likely to become grooved as the drill string is pulled back and forth. Finally, the friction at this groove becomes so great that the bore should be enlarged at the curve. The reamer of this invention can clear a bore even at the upper part of a curved wall.

Another difficulty in;reaming sometimes arises from debris accumulated under the reamer. This clogs the cutters and causes them to wear unevenly. Stresses concentrate at worn or weak points and cause faulty reaming and breakage of parts. For example, a roller cutter may Wear lop-sided and tend to drag and finally to break the cutter shaft. Hard rocky formations may accentuate these faults that retard reaming.

The reamer should be versatile also in utilizing the drilling mud that is pumped through the bore to remove debris and to facilitate drilling. Such mud is heavy and This difficulty is especially severe to daytime drillers. As these operators drill onlyipart of the time they need to clear the mud and cuttings out of the bore before stopping; merely running the drilling fluid without drilling is not sufficient. This reamer facilitates flushing, both in reaming and in clearing the bore.

Sometimes a driller desires to ream at one place and thento ream at another part of the bore without removing the drill. The present invention provides means to accomplish this succession of enlargements; the reamer is 2,868,510 Patented Jan. 13, 1959 simply used at one place, then latched, moved to another elevation, unlatched and used again. This may be repeated as desired and may be carried out regardless of the type of formation or the accumulation of debris or the deviations of a bore, or the presence or absence of easing. In fact, this under-reamer may even be unscrewed from the bottom drill and raised to ream some area without having to lift the entire drill. This might be desirable; for example, where an undercut is desirable to straighten a bore, or to relieve a tight bore or to enlarge a bore for packing. This under-reamer is versatile under these and many other varied conditions.

For such repeated and flexible operations, at will, the reamer must operate positively despite severe conditions. The actuating means for the reamers must be adequate and strong enough for difiering kinds of earth formation. The operating means must be kept clear of debris, particularly clear from accumulations of the drillingmud that flows through the drill stem. Such mud is heavy, and on upward flow may contain cuttings, and the sediment continually tends to clog moving elements in a drill. A suitable reamer must be locked in closed position when not cutting and so locked regardless of the presence or absence of casing. The locking means .must be simple, for both positiveness of operation and requirements of manufacture. The locking means should be 'easy to lock and to unlock repeatedly without need to withdraw the reamer from the well here, yet such means must not interfere with normal drilling operations when the reamer is idle. The under-reamer of this invention is intended to operate positively 'under such varied requirement. It is intended to be driven against earth formations and bore blockages of any sorts, and intended to be locked easily whether within a pipe or not and yet, to be clear for reaming as soon as released. The repeating locking and unlocking means as well as the reaming itself do not depend on fluid but operate with fluid or Without fluid, or with fluid being forced either up or down the reamer.

The nature and usefulness of this invention will be apparent from the following illustrative description thereof, including a preferred form, and from the accompanying drawings.

In the drawings:

Fig. 1 is a longitudinal view of a preferred form of this invention, with the reamer cutters folded to inactive position.

Fig. 2 is a vertical partial section of this same form of under-reamer, showing ends of the body threaded for insertion into a drill string and showing the reamer cutters in full line folded down to inactive position and in dotted line elevated to reaming position.

Fig. 3 is a section across the under-reamer body along the line 3-3 of Fig. 1, showing reamer heads or naves.

Fiv. 4 is a section across the body along the line 4-4 of Fig. 1, showing the connections of the reamers to the piston.

Fig. 5 is a vertical section enlarged of a portion of the under-reamer body, showing a piston and associated area.

Fig. 6 is a section across the under-reamer body along the line 6-6 ofFig. 5, showing a piston and latch area, and i Fig. 7 is an enlarged vertical view in partial section of part of a reamer lock.

Fig. 8 is a longitudinal view of a lock release or actuator element used with the piston latch shown in these drawings.

This invention will be explained with particular reference to the form and operation ofthe embodiments shown in the drawings.

Advantages of this invention are attained by providing .1 3 a repeating lock to hold the reamers in lowered, inactive position, with unlatching means controlled from within the bore of the drill string for repeated unlocking of the reamers to permit their elevation to working position whenever desired. The reamers are returned to latching position, at any time simply by raising the drill a short distance. The whole operation is. carried out repeatedly from the top of the drill string Without necessarily stopping the flow of drilling fluid through the drill string and without interfering with normal drilling at the bottom of the bore.

Certain advantages of this invention further are directed to improvement of the rotary under-reamers that are expanded well above the bottom of. the bore. This invention provides the reamer head or nave with a housing ceiling of such slope in conjunction therewith that the reamer shafts slope upwardly to as much as approximately 115 and there held in floating, balanced condition while drilling. These structures and their advantages appear in the further description of this invention.

An embodiment of the under-reamer illustrated in Figs. 18 is now to be described.

In these figures, under-reamer body 22 is threaded top and bottom, for insertion into some intermediate part of a drill string. There are no inner pipes. A bore extends centrally throughout the body while recesses through the body wall toward the bottom form housing for expansible under-reamer cutters, here shown as three spaced equally around the body. These are rotary cutters 23 mounted on axle pins 24 that extend from heads or naves 25. These heads are pivotally mounted in their housing on cross-pins 26 that extend through the wall and housing. The ceiling 2'7 of nave 25 slopes upwardly so that in conjunction With the nave and the axle cutters 23 tilt upwardly markedly more than 90, preferably to 115 or so. Thus the cutter ends slope down away from the body, as shown in Fig. 2.

Within the body above the reamers a short piston 28 is movable downwardly under force of coil spring 29 mounted on top of the piston. Piston 28 is connected to the inner part of naves 25, as by links 30, so as to pivot the cutters radially of the body. Thus reamer cutters 23 are raised. When cutters 23 are pushed downwardly, as by contact with bore walls, the nave pivots to push piston 28 upwardly.

The top of coil spring 29 on top of piston 28 seats up against an adjustable abutment 31. This abutment extends upwardly in the form of a pipe externally threaded for connection within the threaded upper nipple end of body 1 and has a slotted top, so that screw adjustment of the spring 29 compression is simple. This in turn adjusts the buoyancy or upward bite of these rotary cutters in under-reaming a bore.

These elements within the body bore are themselves open longitudinally, so that an inner bore extends through abutment 31, spring 29 and piston 28. Thus flow of drilling fluid through the reamer continues, if drilling fluid is used. However, operation of this invention does not require any drilling fluid.

A grab-head mandrel 32 rides freely within the inner bore, within adjustment member 31, with the grab head above the top of member 31. This mandrel extends down so it can bear or strike upon the top of piston 28, when the piston is in upper position with the reamer cutters down. Thus mandrel 32 may be dropped upon piston 28. It may be raised therefrom by a line or grab tool to engage the grab head, or in the case where drilling fluid is used, the raising and dropping occur automatically by the drilling fluid.

Action of drilling fluid on mandrel 32 results from the structure of the mandrel, as illustrated in Fig. 7. Mandrel 32 is substantially a float or tube closed at the top to form an upper chamber. Suitable upper enlargement of the tube increases the effectiveness of this tube as a float, by increasing its buoyancy. This is such that mandrel d 32 rises in the usual heavy drilling fluid. This, however, tends to be. offset by downflow of the fluid through the bore of adjustment tube 31. In operation, mandrel 32 finds substantial equilibrium at some point off piston 28, dependent on factors of weight, buoyance and fluid flow. increase of fluid down flow, as by increased pumping above the drill, forces mandrel 32 down upon the piston. It will be observed that the bottom of mandrel 32 is enlarged somewhat to increase volumetric displacement and to form a good seat upon the piston. Also, it will be observed that toward the bottom of the enlarged upper chamber of float mandrel 32, the stem contains opening 41 through toits bore 42, to stabilize this mandrel in upright position, to minimize plugging, and to increase sensitiveness and rapidity of response to increased pumping of the fluid. It is clear that mandrel 32 contains entrapped air, particularly in its upper part above opening 41.

Mandrel 32 acts to unlatch means that lock the piston 28 in upper or inactive position and the rotary reamer cutters in lower or inactive position. Mandrel 32 in this respect is termed a lock key or actuating tube. Its operation will be apparent with description of the latch means, which-with a blocking element form the lock.

Round detent elements 33, such as balls, are housed in individual bores 38 within the wall, of piston 28. These are opposite to complementary bores, or preferably to shallow receiving groove 34, in the inner wall of body 22, such as the three balls 33 shown in Fig. 6 arranged at equal distances around piston 28. These ball detents and their holding recesses preferably are close to the top of piston 28, though they may be disposed lower. Suitable means are applied to keep these ball latches yieldably extended in their housing so as to lock and unlock the piston and the reamer cutters.

Mounting of-these ball latchesand associated operating elements is shown inFigs. 6 and 8' in a form at present preferred.

Fig. 8 shows in vertical enlarged view partly in section a portion of the lock with one of the ball latches and associated region of the piston and release for thepiston. The housing 38 in piston 28 for ball 33 is open outwardly sufficiently for the ball to project into shallow groove 34 in body wall 22. The ceiling and the floor of housing 38 diverge inwardly so as to form v an inclined path and to exert inward thrust against the outer portion of the ball. Thus the constant impulse of large spring 29 uponpiston 28, tends'to unlatch ball 33 inwardly from its groove 34. A retainer or blocking element fits'inside the piston against balls 33. This is in the form of a light ring or cup 35, open centrally for flow of drilling fluid but oifering sufficient top to seat the bottom of mandrel 32, the lock key or actuator. Cup 35 sets upon a light coil spring 36 that is seated upon a retaining ring 37 with sufficient play for cup 35 to be depressed from -a normal ball-retaining position sufliciently for ball 33 to move from its locking groove 34. This is accomplished by impact of key 32 upon cup 35. This unlocking movement is facilitated and limited by the rounding or beveling of the upper surfaced cup 35 so that ball 33 rolls slightly upon the upper surface of the blocking ring 35. Here the downwardly moving piston 28 jams or locks ball 33 against the ring. Then piston, ball, cup, and spring all move down together in the bore of body 22.

Movement of piston 28 is linked to raising or lowering of rotary reamers 23 through link element 30. As shown in Fig. 2, pivotally connected to the lower part of piston 28 zand to the inner end of reamer nave 25, is one link foreach individual cutter. By this linkage, downward movement of piston 28under action of spring 29 pivots each rotary cutter 23 about its cross pin 26 until the top of nave 11 is stopped by the ceiling of its housing. At this position, the ceiling limits the upward tilt of the cutter and its axle 24 to more than ninety degrees, up to about In reverse action, raising eamer body 22, as bylifting the'drill string, causes the wall of a smaller or unreanied bore to contract the cut- Qters 23 to downward or Withdrawn position in their housing',.at the sametime pivoting nave 11 to push :in a bore, he unlatches the reamers by dropping the actuator or key mandrel 32. This by impact depresses cup 35 within piston 28, for spring 36 is relatively light. Only slight and momentary depression is sufficient to unlatch the piston. Depression of a fraction of the radius of detent ball. 33 is sufiicient, for sloping walls of the ball housing groove 34 and the inwardly slanting rim of cup 35 readily permit the constant downward pressure from the relatively heavy spring 29 to roll ball 33 into the piston enough to be free from body wall 22. Then under continued pressure of large spring 29, the entire piston assembly with ball 33 and blocking cup35 move down together. i i

This actuating impact from dropping mandrel 32 with the consequent unlocking action occurs whether or not drilling mud is flowing. This action is clear when no drilling mud is being used, for then mandrel 32 is simply dropped from wherever it may have been held. 1 When drilling mud is being used, it flows normally down through the drill bore that extends through piston 28. In such flow, hollow mandrel 32 simply floats at some equilibrium point above piston 28. Increase of flow of the mud overcomes this equilibrium and forces mandrel 32 down to impact upon cup 35 of piston 2S,thus unlocking the piston as already explained. That is, the piston is unlocked simply by increasing the pumping of drilling mud, even momentarily.

As explained, this unlocking serves to elevate the reamer cutters to reaming position. At the same time, it serves also to cause piston 28 to uncover diverting channels 39 in the wall of reamer body 22. These direct drilling fluid from the reamer bore through wall 22 to the region just above the cutters 23. This flow keeps the cutters clear, especially at the junction of cutter shaft and nave. This diversion of fluid tends to relieve the .higher flow from pumping that had caused the piston to unlatch. Excess of fluid flows through the bore in piston 28. One effect of this entire action is to notify the driller when unlatching occurs, for a distinct release is felt at the pumps when the diversion channels 39 open. The driller may then regulate his pumps as reaming requires. A feature of this invention is that this rearner lends itself to backward or upward flushing with the drill fluid. An operator may reverse flush as they suspend operations and so leave the reamer clear to resume operations later. This is especially valuable to daylight operators who are idle part of the time. Another advantage of the latitude of operation from controlling this reamer simply by the drilling fluid, if fluid is used, or the key mandrel if desired, is that the driller may ream at one point, then simply move the drill string up or down and ream at another point. He may ream out pockets in the drill hole or may straighten the bore wherever desired. He may accomplish these actions without necessarily stopping normal or bottom drilling.

Certain subject matter of this application is found also in my copending application, S. N. 200,425 filed December 12, 1950, now Patent 2,790,625.

It will be evident that variation and equivalent construction fall within the novel features of this invention set forth in the accompanying claims. However, in accordance with the patent statutes, this invention has been explained and the principles thereof and their best mode of application described, to enable those skilled in the art to make and use this invention.

What is claimed is: a

1. An expansive earth under-reamer adapted to straighten an earth-bore, comprising a tubular body having ends each adapted to fasten into a rotary drill string, containing a central tubular opening, housing-openings in the wall of the body, individually rotatable reamers mounted in the wall to swing radially into or outwardly from the housing-openings, and piston means movable up and down within the central tubular opening and connected to swing the reamers, resilient means mounted in one end of the tubular body and bearing down against the piston means to bias the reamers outwardly, a movable stop bearing against the resilient means and held at one end of the tubular body, the stop having adjustment means to regulate said piston and'reamer bias, the adjustment means being near to and readily accessiblefrom the end of the tubular body in which the resilient means is mounted, and re-latching lock means for the reamers having a movable element interengaging the body and the piston, there being complemental recessive wall portions in the tubular body and in the piston adapted to receive said movable element, for limited play therebetween to positions to lock and to unlock the piston under the bias of the adjustable resilient means, and means to move the element to the stated positions between said walls.

2. An expansible earth under-reamer adapted to straighten an earth bore, comprising a tubular body, having ends adapted to fasten into a rotary drill string, housing-openings in the wall of the body, individually rotatable reamers mounted in the wall to swing radially into and outwardly from the housing openings, means comprising a resilient member within the body and connected to the reamers to swing and to bias the reamers outwardly to cutting position, the housing openings having ceilings slanting upwardly and the reamers having naves with upper surfaces adapted and positioned to abut the upwardly-slanted housing ceilings on outward swing of the reamers, said upward ceilings and nave surfaces being directed upwardly between and from the tubular body to slant the reamers generally upwardly, whereby upper surfaces of the reamers are effective to form an undercut upwardly rising face in the walls of the earth bore.

3. An expansive earth under-reamer having a tubular body with ends each adapted to fasten into a rotary drill string and with individually rotatable reamers housed and pivoted in the body wall, within the body a vertically movable annular member having an opening therethrough to convey drilling fluid in either direction, reamer-engaging means on the annular member to swing the reamers in or out as the annular member rises or falls, re-latching lock means to hold the reamers in idle position in their housing comprising an element repeatedly movable to in terengage and to release the annular member with respect to the body, the walls of the body and of the annular member being recessed to interengage and to release said element, means to bias said movable element to one of said walls, and means to relieve said bias, said relief means comprising a buoyant float element adapted to remain above the annular member in a stream of drilling fluid of given buoyancy and to fall against and close the opening in the annular member on increase of flow of the drilling fluid, whereby repeated increase and decrease of pumping rates of drilling fluid repeatedly lock and unlock the reamers to swing from the body.

downwardbias thereon, re-latching lock means to hold the piston in given positiontin: the body comprising a latch, complementally recessive body and piston walls adapted for locking interengagement by the latch, a member movable to bear against the latch to hold it in said locking engagement, and removable from saidbearing position, means to bias the movable member against the latch in said locking position, means to relieve said bias, the compression spring thereupon removing the latch from locking position and moving the piston downwardly to swing the reamers outwardly, the piston, latch and the movable latch-biasing member being formed and adapted tov return to locking position on inward swing of the reamers.

5. An expansive earth under-reamer having a tubular body with ends adapted to fasten into a rotary drill string and with individually rotatable reamers pivotally mounted in the body walls to swing in and. out therefrom, a vertically movable piston within the body, means connecting the reamers with the piston to pivot the reamers, a relatively heavy spring mounted within the body and adapted to push the piston downwardly, together with re-setting lock means to hold the piston in given position in the body, comprising a ball latch, complemental recesses in the body, and piston walls to receive the ball in interlocking engagement, an annular member Within the piston having a wall portion adapted to bear against the ball latch to maintain its interlocking position in said recesses,

said annular member having an inwardly receding wall 1 portion to receive the ball latch away from said interlocking position, a relatively light spring mounted within 1 annular member and the piston contain an opening therethrough for how of drilling fluid in either direction, the under-reamer comprising a closure member having a bottom formed to fit into the opening through the annular member to prevent flow of drilling fluid therethrough, said closure member being tubular and open at the bottom and closed at the top, to form a buoyant float adapted to rise and fall under varying flow of drilling fluid.

References Cited in the file of this patent 

